System-wide time synchronization across power management interfaces and sensor data

ABSTRACT

A power management control system for an information handling system is disclosed. The power management control system includes a power management interface bus interfacing a plurality of devices, where one or more of the devices is each associated with a time clock. The power management control system further includes a management agent interfacing the power management interface bus. The management agent is configured to: receive a system time; synchronize the one or more time clocks based, at least in part, on the system time; and maintain synchronization of the one or more time clocks, at least in part, via a set of telemetric primitives.

TECHNICAL FIELD

The present disclosure relates generally to information handling systemsand, more particularly, to systems and methods for system-wide timesynchronization across power management interfaces and sensor data.

BACKGROUND

As the value and use of information continues to increase, individualsand businesses seek additional ways to process and store information.One option available to these users is an information handling system.An information handling system generally processes, compiles, stores,and/or communicates information or data for business, personal, or otherpurposes thereby allowing users to take advantage of the value of theinformation. Because technology and information handling needs andrequirements vary between different users or applications, informationhandling systems may vary with respect to the type of informationhandled; the methods for handling the information; the methods forprocessing, storing or communicating the information; the amount ofinformation processed, stored, or communicated; and the speed andefficiency with which the information is processed, stored, orcommunicated. The variations in information handling systems allow forinformation handling systems to be general or configured for a specificuser or specific use such as financial transaction processing, airlinereservations, enterprise data storage, or global communications. Inaddition, information handling systems may include or comprise a varietyof hardware and software components that may be configured to process,store, and communicate information and may include one or more computersystems, data storage systems, and networking systems.

As power consumption and power management become further developed,there is a greater need for incorporating sensor sample temporal datawithin the system power management control system, and eventually acrossmultiple systems. In recent years, polling of sensor data was onlyrequired in the low seconds to enable early usage models such as:long-term average system power consumption; power capping/throttling forthermal management; or power capping to a long-term average ceiling.Tight temporal coordination of control and telemetry was not required.

More recent usage models—such as power capping to a PSU (power supplyunit) current output limit, power capping to an external circuit breakeror PDU (power distribution unit), enhanced performance per wattoptimization, among others—require sensor data polling in the tenths ofseconds. Example control systems may read power sensors up to 10 Hz,DIMM (dual in-line memory module) thermal sensors up to 8 Hz, and mayadjust system performance states at up to 4 Hz. These usage modelsrequire only loose coordination of control and telemetry, which isassumed to be much faster than the polling rate and control loop time.

However, next generation usage models may require control and telemetryin the 100s to 1000s Hz or more, where it may become critical that thepower- and thermal-related sensor data be time-correlated across varioussubsystems (PSUs, voltage regulators, thermal sensors, etc.). Currentstate-of-the-art power management buses, interfaces, and methods do notprovide the required timestamp and time-correlation methods to supportthese usage models.

SUMMARY

The present disclosure relates generally to information handling systemsand, more particularly, to systems and methods for system-wide timesynchronization across power management interfaces and sensor data.

In one aspect, a power management control system for an informationhandling system is disclosed. The power management control systemincludes a power management interface bus interfacing a plurality ofdevices, where one or more of the devices is each associated with a timeclock. The power management control system further includes a managementagent interfacing the power management interface bus. The managementagent is configured to: receive a system time; synchronize the one ormore time clocks based, at least in part, on the system time; andmaintain synchronization of the one or more time clocks, at least inpart, via a set of telemetric primitives.

In another aspect, a method for providing a power management controlsystem for an information handling system is disclosed. The methodincludes: providing a power management interface bus interfacing aplurality of devices, where one or more of the devices is eachassociated with a time clock; providing a management agent interfacingthe power management interface bus, where the management agent isconfigured to receive a system time; synchronizing the one or more timeclocks based, at least in part, on the system time; and maintainingsynchronization of the one or more time clocks, at least in part, via aset of telemetric primitives.

In yet another aspect, a method for providing system-wide timesynchronization across power management interfaces is disclosed. Themethod includes: providing a set of primitives to a controller toretrieve and control time information, at least in part, with one ormore of the primitives, where the time information is associated with aplurality of devices coupled to a power management interface bus, andwhere one or more of the devices is each associated with a time clock;and providing a set of telemetric primitives to the controller tosynchronize the one or more time clocks based, at least in part, on oneor more of the telemetric primitives and timestamp information receivedvia the power management interface bus.

The present disclosure provides for comprehensive time and datasynchronization for power management interfaces. Certain embodiments ofthe present disclosure are directed to a power management domain withinan information handling system. Certain embodiments may provide fortime-correlation of power- and thermal-related sensor time clocks anddata across various subsystems. Certain embodiments may synchronizesystem time between systems and/or subsystems to very high accuracy andmay be extended to synchronize power management sensors beyond a singlesystem. Certain embodiments extend power management interfaces toincorporate an array of commands, primitives, and/or extensions tosupport an arbitrary level of time synchronization accuracy within thepower-managed domains of a system and/or across systems. Certainembodiments contemplate usage models include allocating VMs (virtualmachines) to sockets, cores, and/or physical memory based, at least inpart, on one or more of real-time subsystem power usage and efficiencypoints, charge-back of power utilization to a process or VM, fine-grainperformance-per-watt optimization, migration of processes and VMs tooptimal subsystems, subsystem level power capping, and right-sizing ofvoltage regulators. Time primitives, data formats, and clocksynchronization methods allow power management interfaces to providehighly accurate sensor data time stamping to a system power managementagent.

Thus, the present disclosure provides systems and methods forsystem-wide time synchronization across power management interfaces andsensor data. Other technical advantages will be apparent to those ofordinary skill in the art in view of the specification, claims anddrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete understanding of the present embodiments and advantagesthereof may be acquired by referring to the following description takenin conjunction with the accompanying drawing, in which like referencenumbers indicate like features.

FIG. 1 is a simplified schematic diagram of an information handlingsystem and power management system topology for system-wide timesynchronization across one or more power management interfaces, inaccordance with certain embodiments of the present disclosure.

FIG. 2 is a simplified schematic diagram of an example datacentertopology in which certain embodiments of the present disclosure may beimplemented to provide system-wide time synchronization across one ormore power management interfaces, in accordance with certain embodimentsof the present disclosure.

FIG. 3 is a flow chart for one example method of sensor clockinitialization, calibration, and operation, in accordance with certainembodiments of the present disclosure.

FIGS. 4A and 4B illustrate the prior art linear data format.

FIG. 5A illustrates a delta value format, in accordance with certainembodiments of the present disclosure.

FIG. 5B illustrates a compact linear data format, in accordance withcertain embodiments of the present disclosure.

FIG. 5C illustrates a high-precision delta time format, in accordancewith certain embodiments of the present disclosure.

FIG. 5D illustrates a compact delta time format, in accordance withcertain embodiments of the present disclosure.

While embodiments of this disclosure have been depicted and describedand are defined by reference to exemplary embodiments of the disclosure,such references do not imply a limitation on the disclosure, and no suchlimitation is to be inferred. The subject matter disclosed is capable ofconsiderable modification, alteration, and equivalents in form andfunction, as will occur to those skilled in the pertinent art and havingthe benefit of this disclosure. The depicted and described embodimentsof this disclosure are examples only, and not exhaustive of the scope ofthe disclosure.

DETAILED DESCRIPTION

For purposes of this disclosure, an information handling system mayinclude any instrumentality or aggregate of instrumentalities operableto compute, classify, process, transmit, receive, retrieve, originate,switch, store, display, manifest, detect, record, reproduce, handle, orutilize any form of information, intelligence, or data for business,scientific, control, or other purposes. For example, an informationhandling system may be a personal computer, a network storage device, orany other suitable device and may vary in size, shape, performance,functionality, and price. The information handling system may includerandom access memory (RAM), one or more processing resources such as acentral processing unit (CPU) or hardware or software control logic,ROM, and/or other types of nonvolatile memory. Additional components ofthe information handling system may include one or more disk drives, oneor more network ports for communication with external devices as well asvarious input and output (I/O) devices, such as a keyboard, a mouse, anda video display. The information handling system may also include one ormore buses operable to transmit communications between the varioushardware components.

For the purposes of this disclosure, computer-readable media may includeany instrumentality or aggregation of instrumentalities that may retaindata and/or instructions for a period of time. Computer-readable mediamay include, for example without limitation, storage media such as adirect access storage device (e.g., a hard disk drive or floppy disk), asequential access storage device (e.g., a tape disk drive), compactdisk, CD-ROM, DVD, RAM, ROM, electrically erasable programmableread-only memory (EEPROM), and/or flash memory; as well ascommunications media such wires, optical fibers, microwaves, radiowaves, and other electromagnetic and/or optical carriers; and/or anycombination of the foregoing.

Illustrative embodiments of the present invention are described indetail below. In the interest of clarity, not all features of an actualimplementation are described in this specification. It will of course beappreciated that in the development of any such actual embodiment,numerous implementation-specific decisions must be made to achieve thedevelopers' specific goals, such as compliance with system-related andbusiness-related constraints, which will vary from one implementation toanother. Moreover, it will be appreciated that such a development effortmight be complex and time-consuming, but would nevertheless be a routineundertaking for those of ordinary skill in the art having the benefit ofthe present disclosure.

Certain embodiments of the present disclosure are directed to a powermanagement domain within an information handling system (e.g., aserver). Certain embodiments may provide for time-correlation of power-and thermal-related sensor time clocks and data across varioussubsystems. Certain embodiments may synchronize system time betweensystems and/or subsystems to very high accuracy and may be extended tosynchronize power management sensors beyond a single system. Certainembodiments extend power management interfaces to incorporate an arrayof commands, primitives, and/or extensions to support an arbitrary levelof time synchronization accuracy within the power-managed domains of asystem and/or across systems. Certain embodiments provide for usagemodels include allocating VMs (virtual machines) to sockets, cores,and/or physical memory based, at least in part, on one or more ofreal-time subsystem power usage and efficiency points, charge-back ofpower utilization to a process or VM, fine-grain performance-per-wattoptimization, migration of processes and VMs to optimal subsystems,subsystem level power capping, and right-sizing of voltage regulators.Time primitives, data formats, and clock synchronization methods allowpower management interfaces, that may implement industry standardprotocol PMBus (Power Management Bus), SMBus (System Management Bus) andothers, to provide highly accurate sensor data time stamping to a systempower management agent.

FIG. 1 is a simplified schematic diagram of an information handlingsystem 100 and power management system topology 120 for system-wide timesynchronization across one or more power management interfaces, inaccordance with certain embodiments of the present disclosure. The powermanagement system topology 120 may be implemented in an informationhandling system or across a plurality of information handling systems.The information handling system 100 may include one or more processors105 communicatively coupled to memory 115 and a north bridge 110. Thenorth bridge 110 may be communicatively coupled to a south bridge 120.The south bridge 125 may be communicatively coupled via an interface 130to a controller 135. In certain embodiments, the interface 130 may be abus according to the SMBus standard. The controller 135 may be orinclude a systems management hardware and software solution, such as aBaseboard Management Controller (BMC), a Management Engine (ME), or anintegral part of a Remote Access Controller.

A management controller 140 may be coupled to controller 135 andoperable to provide a proxy pass-through control/interrupt from thecontroller 135 to one or more power control/status devices 150 via aninterface 145. In certain embodiments, an interface 145 such as a busaccording the PMBus standard may couple the power control/status devices150 to one or both of the south bridge 125 and management controller140. For example without limitation, the power control/status devices150 may include voltage regulator command/control, power supplycommand/control, subsystem monitoring/control, and may include any ofvarious power management elements and sensors that may be associatedwith various subsystems. Example sensors may include AC and DC voltage,current, and power sensors, temperature sensors, fan RPM sensors, etc.In certain embodiments, one of more of the power control/status devices150 may include calibrated responder devices 155. As disclosed infurther detail herein, a calibrated responder device 155 may provideprecisely know command and response latency.

FIG. 2 is a simplified schematic diagram of an example datacentertopology 200 in which certain embodiments of the present disclosure maybe implemented to provide system-wide time synchronization across one ormore power management interfaces, in accordance with certain embodimentsof the present disclosure. A plurality of information handling systemsmay be housed in a data center, which may include several rows of racksof information handling systems. The information handling systems mayinclude computational units, which provide a computational power thatmay be distributed across several information handling systems. By wayof example, the datacenter topology 200 may include a management console205 communicatively coupled, with a one-to-many managementcorrespondence, to one or more of servers 210, storage 215, one or moreswitches 220, and various subsystems 225, each element being associatedwith an individual time clock and one or more subsystem sensors. Adatacenter workload distribution manager and virtualization workloaddistribution manager, generally indicated at 230, may likewise includean individual time clock and be communicatively coupled to themanagement console 205 and other elements of the datacenter. Byutilizing system-system time synchronization as disclosed herein,simultaneous per-element power management across systems with topologiessuch as example datacenter topology 200 may be achieved to a high levelof accuracy and may allow datacenter-wide optimized scheduling of tasks,virtual machines, resources, etc. with synchronized power managementclocks and subsystem sensors.

System time may be provided via a counter of 32-64 bits, with resolutionin the nanoseconds to milliseconds. A zero count may correspond to aspecific date, such as Jan. 1, 1900. Embodiments of the presentdisclosure do not depend on specific clock implementation, but provideflexibility to maintain one or more synchronized power-managed sensorclocks to the accuracy required for one or more applications.

Moreover, certain embodiments of this disclosure may be used tosynchronize system time between systems to very high accuracy. As wouldbe appreciated by one of ordinary skill in the art having the benefit ofthis disclosure, certain embodiments may be used in conjunction withvarious industry standard methods to distribute system time acrossdevices on a common network. By way of example, the standards includethe following, which are hereby incorporated by reference: ITS (InternetTime Service), NTP (Network Time Protocol, specified in RFC 778, RFC891, RFC 956, and RFC 1305), GPS (The Global Positioning System), PTP(Precision Time Protocol, per IEEE 1588-2002 and 1588-2008 standards),and various Military Networks standards. Methods according to suchstandards allow system-system clocks to be maintained to one millisecondor better.

A BIOS (Basic Input/Output System) of an information handling system maytransfer a system time, illustrated as TIME CLK 211, on a periodic basisto a systems/power management agent (“management agent”) that mayutilize one or more controllers and/or management elements. Themanagement agent is typically a firmware or software program executingon controller 135 or on management controller 140 (or CPU 105 or anyother suitable element within the information handling system). Amanagement agent time may be synchronized to system/operating systemtime and then distributed to power control/status devices. This allowsany clock drift within a system to be corrected and clocks acrossmultiple systems, and/or elements within a system, to be keptsynchronized.

The management agent may initialize, calibrate, and maintain clock timeacross all power management elements and sensors. By way of example, thefollowing primitives may be provided to facilitate initialization,calibration, and maintenance of clock time synchronization.

-   -   Write Time (absolute) to one (single) or more nodes (e.g., per        Broadcast or Group Command protocols)    -   Adjust Time by X (relative)    -   Read Time (absolute)    -   Read Supported Time Base Precision    -   Mark Time (causes sensor to snapshot a new time baseline for        future telemetry with delta-time)        The primitives disclosed herein may be implemented in user- or        manufacturer-defined messages and/or opcodes (operation codes),        or eventually be folded into industry standards. For instance,        the PMBus standard supports 256 MFR_SPECIFIC_COMMAND_EXT and 256        PMBUS_COMMAND_EXT command set extensions, which allow        manufacturers to implement additional commands beyond the        standard 256 command codes.

FIG. 3 shows a flow chart 300 for one example method of sensor clockinitialization calibration, and operation, in accordance with certainembodiments of the present disclosure. The system may be powered on atstep 305. Initialization may include determining (discovery of) one ormore power sensor elements and/or topology at step 310. Initializationmay further include reading one or more sensor devices for supportedcommand types, clock, and/or data precision, as indicated at step 315.At step 320, system clock time from BIOS/operating system may beobtained and distributed to one or more management agents.

Calibration may include writing Broadcast/Group time base to one or moresensor devices at step 325. At step 330, calibration may further includereading clock and sensor with timestamp from each element, including“calibrated” responder in certain embodiments. Time correction factorsmay be computed for one or more sensors device at step 335. In certainembodiments, one or more of steps 325, 330, and 335 may be repeated anysuitable number of times to improve calibration based on mean, standarddeviation, and/or recomputed time correction factors. Successiveapproximation may be used, combined with averaging of readings, toobtain arbitrary calibration accuracy. Certain embodiments may use a“Known Good”/“calibrated” responder with known latencies to calibrateother devices on the topology and thereby remove clock uncertainty.

After calibration, the method may transition to normal operation. Thenormal operation stage may include broadcasting a “Mark” command tosnapshot one or more new time bases for delta-time responses, asindicated at step 340. At step 345, before the one or more clocksapproach a roll-over limit of delta-time formats, the method maytransition to re-synchronization. At step 350, the method mayre-calibrate by periodically adjusting for crystal & oscillator clockdrift. The method may loop to step 320 for additional iterations.

Thus, the flowchart 300 illustrates one example method of initializationand calibration of that may be applied to various sensor clocks. Itshould be understood that the example method may be subject toconsiderable modifications depending on specific implementations.Various algorithms may employ broadcast time and read-back from eachdevice on the topology to cross-calibrate and “triangulate” to determinelatencies to be used to null out time.

Once the clocks are synchronized, the following telemetry primitives maybe used.

-   -   Read parameter with Timestamp When Last Sampled (absolute)    -   Read parameter with Timestamp When Placed on Bus (absolute)    -   Read parameter with Delta-Time from Last Mark Time (relative)    -   Schedule operation or sensor update at X time (relative or        absolute)

Power management buses, such as PMBus standard buses, support generaldata formats, but these formats are not optimal for minimizing busbandwidth and latency. As is known in the art, a linear data format inPMBus may be used for commanding and reporting parameters. The lineardata format is a two-byte value with an 11-bit, two's complementmantissa and a 5-bit, two's complement exponent (scaling factor). FIG.4A illustrates the format of the two data bytes, where Y corresponds tothe mantissa and N corresponds to the exponent. The “real world” value Xmay be represented by the equation: X=Y*2^(N).

The data bytes for commanding and reporting parameters may require 3bytes when using the linear voltage data format. FIG. 4B illustrates theformat of the three data bytes. One data byte is an output voltage modecommand byte that is sent separately from the other two data bytes forthe output voltage-related command. The output voltage mode command byteconsists of bits 0-4 for the exponent (N) and bits 5-7 for the mode. Theoutput voltage mode command byte is sent only when the format of theoutput voltage changes. The data bytes for the output voltage-relatedcommand consist of a low byte and high byte that correspond to themantissa (V). The voltage may be represented by the equation:voltage=V*2^(N). Thus, the linear data formats for PMBus require 2-3bytes for every value.

As most sensors are only applicable in a limited value range, or arevery slowly changing, the following metrological primitives are providedto minimize the interface bandwidth and latency.

-   -   Delta Time—Return time from last Mark    -   Mark Time—Subsequent sensor access provides Delta Time from last        Mark    -   Set Magnitude Base Per Sensor (mV, V, μA, mA, A)—Value return is        based on magnitude resolution    -   Delta Value—Return value difference from last time sensor was        read

FIGS. 5A-D show corresponding primitives formats by way of examplewithout limitation. FIG. 5A depicts an example delta value format,generally indicated at 500. A single byte may provide the necessaryrange and resolution, versus the 2-3 bytes required by the in theexisting art. The delta value format, in signed 2's complement, mayprovide for +/−127 units. Bits 0-6 may be provided for the Delta Valueand bit 7 may be provided for the sign.

FIG. 5B depicts an example compact linear data format, generallyindicated at 505. The compact linear data format may provide for a 2-bitexponent with a 6-bit mantissa, as depicted. Bits 0-5 may be providedfor the mantissa (Y); bits 6 and 7 may be provided for the exponent (N),such that X=Y*2^(N). In an alternative not shown, the compact lineardata format may provide for another delineation such as a 3-bit exponentwith a 5-bit mantissa.

FIG. 5C depicts an example high-precision delta time format, generallyindicated at 510. The high-precision delta time format may provide bits0-13 for a count with a range of 0 to 8,191 units. Bits 14 and 15 may beprovided for the magnitude. As depicted, the magnitude may provide ascale from the nanoseconds to seconds, for example.

FIG. 5D depicts an example compact delta time format, generallyindicated at 515. The compact delta time format may provide bits 0-5 fora count with a range of 0 to 63 units. Bits 6 and 7 may be provided forthe magnitude. As depicted, the magnitude may provide a scale from apre-selected time base to orders of magnitude of ten, hundred andthousand, for example. The time base, for example, may be nanoseconds,microseconds, milliseconds, or seconds. Initializing via “Magnitude BasePer Sensor” may reduce required data handling.

The telemetric and metrological primitives of the present disclosure maybe used for management of multiple sensors. A few of the myriad possiblenon-limiting examples may include: setting time base to X; settingmagnitude to amperes; reading AC current with timestamp when lastsampled; taking a new sample of voltage X milliseconds after receivingthe command; adjusting time base by +5.321 milliseconds; readingtemperature with timestamp; capturing AC waveform when time base=X Buswith sensor data timestamps.

Thus, the present disclosure provides systems and methods forsystem-wide and system-to-system time and data synchronization for powermanagement interfaces and sensors. These systems, formats, and methodsmay reduce power management interface bandwidth and latency. Disclosedmethods may be used to maintain synchronization, and commands forcontrols and telemetry may return data with absolute and/or relativetime. A power management agent may correlate return data and/orschedule/coordinate power control changes. With the fine-grained timesynchronized power telemetry disclosed herein, usage models, such ascharging power utilization to virtual machines and real-timeperformance/Watt optimization, may be supported. While certain examplesherein are disclosed in view of the PMBus protocol, certain embodimentsmay be applicable to all similar interfaces. Additionally, certainembodiments may be integrated and/or adapted with various knownprotocols to facilitate system-system time and data synchronization thatmay allow system-system clocks to be maintained to one millisecond orbetter. Other technical advantages will be apparent to those of ordinaryskill in the art in view of the specification, claims and drawings.

Therefore, the present invention is well adapted to attain the ends andadvantages mentioned as well as those that are inherent therein. Theparticular embodiments disclosed above are illustrative only, as thepresent invention may be modified and practiced in different butequivalent manners apparent to those skilled in the art having thebenefit of the teachings herein. Furthermore, no limitations areintended to the details of construction or design herein shown, otherthan as described in the claims below. It is therefore evident that theparticular illustrative embodiments disclosed above may be altered ormodified and all such variations are considered within the scope andspirit of the present invention. Also, the terms in the claims havetheir plain, ordinary meaning unless otherwise explicitly and clearlydefined by the patentee. The indefinite articles “a” or “an” as used inthe claims are each defined herein to mean one or more than one of theelement that it introduces.

What is claimed is:
 1. A power management control system for aninformation handling system, the power management control systemcomprising: a power management interface bus interfacing a plurality ofdevices, wherein one or more of the devices is each associated with atime clock; and a management agent interfacing the power managementinterface bus, wherein the management agent is configured to: receive asystem time; synchronize the one or more time clocks based, at least inpart, on the system time, wherein the one or more of the time clocks areeach associated with one or more of a voltage regulator, a currentsensor, a voltage sensor, a power sensor, a fan parameter sensor, and athermal sensor; maintain synchronization of the one or more time clocks,at least in part, via a set of telemetric primitives; and time-correlatedata provided by the one or more of the voltage regulator, the currentsensor, the voltage sensor, the power sensor, the fan parameter sensor,and the thermal sensor; wherein the time-correlation is performed, atleast in part, with one or more of a delta value format, a compactlinear data format, a high-precision delta time format, and a compactdelta time format.
 2. The power management control system of claim 1,wherein the management agent is further configured to maintainsynchronization of the one or more time clocks based, at least in part,on timestamp information received via the power management interfacebus.
 3. The power management control system of claim 1, wherein the oneor more of the devices comprises at least two devices, and wherein themanagement agent is further configured to synchronize the one or moretime clocks based, at least in part, on a calibrated responderassociated with one of the devices.
 4. The power management controlsystem of claim 1, wherein the management agent is further configured tomaintain synchronization of the one or more time clocks, at least inpart, with one or more of the delta value format, the compact lineardata format, the high-precision delta time format, and the compact deltatime format.
 5. A method for providing a power management control systemfor an information handling system, the method comprising: providing apower management interface bus interfacing a plurality of devices,wherein one or more of the devices is each associated with a time clock;providing a management agent interfacing the power management interfacebus, wherein the management agent is configured to receive a systemtime; synchronizing the one or more time clocks based, at least in part,on the system time, wherein the one or more of the time clocks are eachassociated with one or more of a voltage regulator, a current sensor, avoltage sensor, a power sensor, a fan parameter sensor, and a thermalsensor; maintaining synchronization of the one or more time clocks, atleast in part, via a set of telemetric primitives; and time-correlatingdata provided by the one or more of the voltage regulator, the currentsensor, the voltage sensor, the power sensor, the fan parameter sensor,and the thermal sensor, wherein the time-correlation is performed, atleast in part, with one or more of a delta value format, a compactlinear data format, a high-precision delta time format, and a compactdelta time form.
 6. The method of claim 5, further comprising:maintaining synchronization of the one or more time clocks based, atleast in part, on timestamp information received via the powermanagement interface bus.
 7. The method of claim 5, wherein the one ormore of the devices comprises at least two devices, and wherein themethod further comprises synchronizing the one or more time clocksbased, at least in part, on a calibrated responder associated with oneof the devices.
 8. The method of claim 5, further comprising maintainingsynchronization of the one or more time clocks, at least in part, withone or more of the delta value format, the compact linear data format,the high-precision delta time format, and the compact delta time format.9. A method for providing system-wide time synchronization across powermanagement interfaces, the method comprising: providing a set ofprimitives to a controller to retrieve and control time information, atleast in part, with one or more of the primitives, wherein the timeinformation is associated with a plurality of devices coupled to a powermanagement interface bus, and wherein one or more of the devices is eachassociated with a time clock; providing a set of telemetric primitivesto the controller to synchronize the one or more time clocks based, atleast in part, on one or more of the telemetric primitives and timestampinformation received via the power management interface bus; receiving asystem time; synchronizing the one or more time clocks based, at leastin part, on the system time, wherein the one or more of the time clocksare each associated with one or more of a voltage regulator, a currentsensor, a voltage sensor, a power sensor, a fan parameter sensor, and athermal sensor; maintaining synchronization of the one or more timeclocks, at least in part, via a set of telemetric primitives; andtime-correlating data provided by the one or more of the voltageregulator, the current sensor, the voltage sensor, the power sensor, thefan parameter sensor, and the thermal sensor; wherein thetime-correlation is performed, at least in part, with one or more of adelta value format, a compact linear data format, a high-precision deltatime format, and a compact delta time format.
 10. The method of claim 9,further comprising configuring the controller to support data transfervia one or more of the delta value format, the compact linear dataformat, the high-precision delta time format, and the compact delta timeformat.
 11. The method of claim 10, further comprising: maintainingsynchronization of the one or more time clocks based, at least in part,on timestamp information received via the power management interfacebus.
 12. The method of claim 10, further comprising: maintainingsynchronization of the one or more time clocks, at least in part, withone or more of a delta value format, a compact linear data format, ahigh-precision delta time format, and a compact delta time format.